The present invention relates to fluid level sensors, and more specifically to low oil sensors for engines.
Fluid level sensors are generally used to determine the level of fluid retained within an enclosure. Some fluid level sensors activate an indicator when the fluid level decreases below a desired fluid level while others automatically shut off the system using the fluid.
In operation, fluid level sensors are positioned directly in a fluid reservoir, or within a smaller enclosure in fluid communication with the fluid reservoir. The enclosure maintains a fluid level proportional to the amount of fluid in the reservoir. One example of an application of a fluid level sensor is a sensor for the oil level within the crankcase of an internal combustion engine. The engine requires a desired amount of oil within the crankcase to properly lubricate the engine during operation. If the oil level is too low, the engine can be damaged due to improper lubrication. A fluid level sensor can be used to determine when the oil level within the crankcase is below a desired level.
Prior art systems often employ the use of a float within a housing to move with the level of fluid as the level of fluid changes. A sensor or an electrical contact can be positioned in the vicinity of the float and can be used to detect when the level of fluid is not within a desired range. The sensor or contact can communicate the condition of the fluid level through a indicator such as a warning light or by automatically shutting off the device that is using the fluid to operate. For example, the float can complete an electrical connection between a ground and an ignition contact to shut off the engine when the float is in a position indicative of low fluid or complete an electrical circuit for an audible indicator or visual indicator.
The use of such a system is generally reliable in shutting off the engine when a low amount of fluid is present. However, signaling a low fluid condition can be inconsistent due to the effect of the vibrations caused by moving parts of the engine, for example. This causes the fluid to move and splash around in the reservoir, thereby causing movement of the float and an unstable contact between the ground and ignition contact. This movement has the potential to prevent the float from grounding the ignition long enough to completely shut down the engine.